Re: [APML] SCT mirror lock

["John Boudreau" <jeboud@mediaone.net>]

> I use a bolt to lock the mirror on my 12" SCT.  I use a single
> bolt, nut, and a short nylon spacer.  I don't use a spring,
> and I've had very good results.

You're lucky. I've used the same type of stabilization bolt also in the
past, and tried it with a nylon spacers and also the more commonly used
springs. Regardless of whether the bolt is used with spacers or springs, it
can only supply a loading in one direction. It still leans heavily upon the
force of the primary mirror spring on a 12" SCT to keep the mirror in place,
apparently that's enough on your scope.

If I recall correctly, Philip Perkins found that he didn't have to use any
stabilizer at all on his 10" SCT; others can't photograph without one (as
you may know, the 10" does not use a primary mirror spring). The production
variances between these scopes is quite large. My 12" only moderately
improved just using a stabilization bolt. This device is much more efficient
and is easier to use, but of course it requires some modification to the
scope.

John Boudreau
jeboud@mediaone.net
http://people.ne.mediaone.net/jeboud/astro.htm
----- Original Message -----
From: "Jason Lewis" <jlewis@nomoon.org>
To: <astro-photo@seds.org>
Sent: Friday, September 21, 2001 4:03 PM
Subject: RE: [APML] SCT mirror lock


> I use a bolt to lock the mirror on my 12" SCT.  I use a single
> bolt, nut, and a short nylon spacer.  I don't use a spring,
> and I've had very good results.  I agree that it is important
> to use some type of mirror lock with the 12".  The spring that
> is inside the mirror housing with this scope makes mirror
> movement especially unpredictable.  I've seen doughnuts in a
> 15 minute exposure made without a lock.
>
> Jason
>
> See Astrophotos at http://www.nomoon.org
> Allen Anti-Telemarketing Society
> http://www.nomoon.org/aats.htm
>
>
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